A novel design method for mechatronic systems, based on knowledge based engineering techniques, is proposed in this research study. The method is particularly suited for mechatronic vehicles which are inherently unstable and require control systems for stabilization. The method is implemented in a dedicated software tool in which physical entities of the product are defined as classes with attributes. Non-physical elements of the system and procedures for the design and analysis of the system are defined as functions with variables. The method has two key features. First, multiphysics simulation models and associated analysis functions are generated automatically within a multidisciplinary analysis and optimization framework. These models are not restricted to geometrical aspects for mechanical design, but also include the system architecture, dynamics, aerodynamics, electronic control systems and associated software codes. Second, for each representation of a design, a dedicated control system is developed completely automatically, based on the multiphysics simulation model, using model inversion control. These two features make it possible to analyse the dynamics and performance of inherently unstable mechatronic vehicles already in the early design phases when the vehicle is still subject to large configuration design changes. The method is demonstrated for the design of a multirotor unmanned aerial vehicle. Thirty thousand possible design solutions are evaluated by the system without manual interference. For each design, a dedicated control system is created and five flight test maneuvers are simulated in order to assess the aircraft performance and flying qualities. A global optimization process is applied for two conflicting requirements and the process is convergent at two optimum solutions.
Abstract. Obtaining a representative loading spectrum that corresponds well to the reality is still one of the greatest challenges for fatigue life calculations and optimal design of the trailer body. A good qualitative and quantitative knowledge of the spectrum leads to more efficient usage of material, a better design of connection points and an overall decrease of the weight of the trailer, which finally results in a significant decrease in the price of a ton of cargo per km. Despite that, the approach is nowadays mostly based on the experience and rules of thumb. It typically results in over-dimensioning of some parts while other parts remain vulnerable to failure due to unknown loading patterns. This paper describes a generic approach to solve the problems mentioned above applied in a research project named FORWARD (Fuel Optimized trailer Referring to Well Assessed Realistic Design loads). The project lasted two years and was carried out in cooperation with several different trailer manufacturers and 1st tier suppliers. The loading history of more than 1000 hours for five trailer types were captured in the shape of strains, accelerations and velocities of various elements of the trailers, enabling reconstruction of the loading in terms of forces and moments acting on the wheels and kingpin. Parallel to this extensive test-campaign, a novel generic physics-based computational approach was developed to predict selected loads encountered during common manoeuvres to all trailer types. The computational approach was validated against test-data and resulted in creating a generic multibody library applicable for all trailer types, and an automated post-processing routine for the large amount of test-data.
The level of software integration in vehicles, such as electric cars and aircraft, is rapidly increasing. Due to the increasing complexity of the embedded control software, significant delays can occur in development programs or even errors can be present in the control software of the final product. In the development of the electric and electronic system (E/E system), the analysis and specification for the architecture of the logical system, technical system and software itself includes many repetitive (manual) processes. Those repetitive processes are time consuming and are prone to errors. This research proposes new methods and tools that allow the designer to take electronic components, including control software, into account already in the conceptual design stage of complex systems. These new methods are based upon the principles of Knowledge Based Engineering (KBE), which is essentially a combination of computer aided design (CAD) and artificial intelligence (AI). The proposed methods can establish the relationship from the logical system architecture to the technical system architecture and finally the software components. Moreover, the proposed tools can model the logical, technical architecture and automatically generate the software components. The software language GDL, which is particularly suitable for the representation of complex systems and the development of KBE applications, has been used to develop the tools. The development of an Anti-lock Braking System (ABS) for a novel electric vehicle configuration has been chosen as test case. Based on a single intelligent product model, that contains the main design parameters of the vehicle specified by the designer, two models are generated automatically; (1) the simulation model of the physical plant and the associated control system, and (2) the control software. For a specific vehicle configuration, the simulation model can be used to test the control system and to optimize the parameters of the control system. In the case of an ABS, a braking maneuver is simulated. Next, the software components are generated automatically. The simulation model is used to test the software components for a range of conditions. The results show that the of the software components are automatically updated when the physical plant of the E/E systems or top level overall design changes. The final source code is wellstructured and easy to understand due to the fact that there is a direct relation between the vehicle design parameters specified in the original product model and the variables and their values in the data model of the software components. The proposed design methods and tools can in principle be applied to any dynamic system with a high level of software integration, such as e.g. unmanned aerial vehicles.
In order to guarantee the stable emission power and good working environment of semiconductor laser, a new hardware circuit is selected and designed to realize automatic optical power control, in which a negative feedback operation amplifier circuit is adopted to form the constant current source, and an optoelectronic feedback to realize closed loop control in this paper. And then, the corresponding steady control circuit is also designed, so that the stable power can be output. The experimental results show that the stability of laser power is better than 0.74% when the system works.
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